In the production of high-quality tissue, machine speed and efficiency are often limited by the performance of the dry end of the machine between the final dryer and the winding station or reel-up. Tissue is extremely delicate and difficult to handle, especially at high machine speeds. As the machine speed is continually pushed higher and higher in an effort to improve productivity, it becomes increasingly difficult to move the tissue web from the dryer to the reel-up without encountering handling problems. In a typical tissue machine, the web is creped from a Yankee dryer by a creping doctor and is then carried in a partly open or free draw to the reel-up. Located in this free draw is a measuring frame supporting measuring equipment for measuring properties of the web such as basis weight and moisture content. The dry end of the machine frequently also includes calendering equipment. In many tissue machines, the free draw tends to be quite long, which exacerbates the problem of handling the web. The web typically is guided to a reel drum that forms a nip with a growing paper roll wound on a reel spool of the reel-up. In most cases, the reel drum is mounted in a fixed position and the reel spool is movable for controlling the nip load in the reel-up.
The conventional type of tissue machine described above has a number of drawbacks that limit the machine speed and/or the quality of the tissue and the uniformity of the properties of the wound roll. The long distance between the creping doctor and the reel-up is conducive to aerodynamic instabilities of the web, which can cause web breaks and other problems. The web stability problems typically necessitate supporting equipment to stabilize the web. The supporting equipment commonly consists of a relatively sophisticated series of foils and/or guide rolls. The long dry end also means that the machine has a relatively large footprint.
Another problem associated with the conventional tissue machine is that because of the great weight of the paper roll it is very difficult to accurately control the nip load by moving the reel spool on which the paper roll is wound. Consequently, nonuniformities in the winding qualities of the paper roll can arise.